Magnetic orientation of liquid crystalline polymers and liquid crystallinity of crystalline polymers

A liquid crystalline copolyester consisting of 60 mol% p-hydroxybenzoic acid/40 mol% ethylene terephthalate units was aligned in a magnetic field (6 T), and the structure and the tensile/thermal properties of these oriented films were studied in comparison to these properties of mechanically stretched films. The elastic modulus of the magnetically oriented films was as high as that of the mechanically stretched films, but the ultimate tensile strength was slightly lower. It was found that the structure of the aligned films viewed in a molecular level as well as a micron level depended on the orientation method used, which might be responsible for the difference in physical properties. Magnetic orientation df crystalline polymers including poly(ethylene-2,6-naphthalate) (PEN) and isotactic polystyrene was reported. The orientation was observed during the induction period of isothermal crystallization from melts, prior to the formation of crystals. The PEN sample crystallized inside the magnet (6 T) exhibited the orientation with the a-axis normal to and the c-axis parallel to the magnetic field in consistent with the diamagnetic anisotropy of the naphthalene ring. In situ FT-IR study demonstrated that the trans conformers in the amorphous phase increase during the induction period, prior to the crystallization.